Liverpool's economy will be stronger if new high-speed rail lines are built, a Government minister has said.

Transport Secretary Patrick McLoughlin made the claim as he attempted to justify controversial plans to spend at least £42.6bn on the High Speed Two (HS2) project.

HS2 will see 250mph train tracks built between London, Birmingham, Leeds and Manchester in a Y-shaped network.

The case for HS2 was boosted after accountancy firm KPMG published a report showing Britain’s economy would be £15bn a year better off with high-speed trains.

Mr McLoughlin said: “It (the KPMG report) addresses that vital question: will HS2 create jobs and growth in the North and Midlands, where they are needed most? The answer is absolutely clear. Yes.

“High Speed Two will make Liverpool stronger. Manchester stronger. Leeds stronger. Britain stronger. A £15bn annual boost to the economy, with the North and Midlands gaining at least double the benefit of the South.”

The Transport Secretary’s speech forms part of a campaign announced by Prime Minister David Cameron to make the case for HS2 in the face of what he called an “unholy alliance” of sceptics.

Recent critics have included Labour’s Alistair Darling, who first approved when he was Chancellor, the Institute of Directors, which dismissed HS2 as “a grand folly”, and the House of Commons spending watchdog, which said the arguments for the project were based on “fragile numbers, out-of-date data and assumptions which do not reflect real life”.

HS2 is also fiercely opposed by some Tory MPs, many representing communities which will be disrupted by construction work and train noise along the route.

But Mr McLoughlin said the UK’s transport network would become “clogged” without the new lines.

He said: “The reason we need HS2 isn’t for its speed, though speed is obviously a benefit. HS2 will allow you to get from Birmingham to Leeds in 57 minutes and from Manchester to London in 68.

“The benefits of faster journeys are easy to explain. But speed is not the main reason for building the new railway. The main reason we need HS2 is as a heart bypass for the clogged arteries of our transport system.”

Critics have dismissed the HS2 project, claiming it will be too expensive, blight the countryside and suck jobs and investment from the Midlands and North to London. There are also some who argue the HS2 funding would be better spent improving existing railways.

HS2 is supported by the Liverpool Chamber of Commerce and Merseytravel which has even suggested the high-speed line between Birmingham and Manchester should continue to Liverpool.